CODEWITHSUNDEEP
javavariablescolorsawt
Hungry Blue Dev
Hungry Blue Dev

Reputation: 1325

Why does java.awt.Color have two variables for every Color?

An excerpt from java.awt.Color:

...
/**
 * The color white.  In the default sRGB space.
 */
public final static Color white     = new Color(255, 255, 255);

/**
 * The color white.  In the default sRGB space.
 * @since 1.4
 */
public final static Color WHITE = white; // My comment: THE SAME!!??
...

As you can see from the above extract, the Color white is assigned to two variables namely Color#WHITE and Color#white this is also the same case for:

 - black     (and BLACK)
 - blue      (and BLUE)
 - cyan      (and CYAN)
 - darkGray  (and DARK_GRAY)
 - gray      (and GRAY)
 - green     (and GREEN)
 - lightGray (and LIGHT_GRAY)
 - magenta   (and MAGENTA)
 - orange    (and ORANGE)
 - pink      (and PINK)
 - red       (and RED)
 ->white     (and WHITE)<-discussed
 - yellow    (and YELLOW)

Initially, I used to think that each color had two names for a reason. But when I checked the source code, I came to know that both of them have the same value!

I want to know why is there such a provision for having two variables for every color?

Is there any specific reason (be it historic, practical, etc.) for such usage?

And finally, which of the two to use in our applications?:

// THIS?:
Color newC = Color.white;

// OR THIS?:
Color newC = Color.WHITE;

Upvotes: 1

Views: 609

Answers (3)

user432
user432

Reputation: 3534

The variables were changed according to Java conventions which says constants to be uppercase only. The lowercase are still there for compatibility and have the same value.

To follow Java conventions you should always use the uppercase constants like:

Color.RED

Upvotes: 6

GyaniPundit
GyaniPundit

Reputation: 133

If you see the source code of Color.java, you will find that both are same only.

public final static Color white     = new Color(255, 255, 255);

and Since 1.4

 public final static Color WHITE = white;

Just because of Java specification which says constant (final static) should be in upper case, a WHITE constant is introduced.

UPDATE:

By convention, the names of constant values are spelled in uppercase letters. If the name is composed of more than one word, the words are separated by an underscore (_).

Upvotes: 3

Rahul Tripathi
Rahul Tripathi

Reputation: 172548

Because they wanted to follow a convention(since JDK 1.4) which says constants should be used in uppercase only. So you should prefer to use:

Color.RED

Upvotes: 3

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